Lens Test: Sigma 24–105mm f/4 DG OS HSM

The latest Sigma “A” lens ranks an A

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As with most of Sigma’s recent glass, it’s also compatible with the company’s unique USB docking station, which allows for firmware updates and focus adjustments.

Sigma continues to expand its impressive line of “Art” lenses, which are characterized by high speed, constant apertures, impressive build quality, and unusually attractive cosmetics. The Sigma 24–105mm f/4 DG OS HSM ($899, street) incorporates Sigma’s relatively new Thermally Stable Composite (TSC) plastic, boasts two SLD and two FLD elements, and is stabilized. On APS-C bodies, it functions (approximately) as a 36–157.5mm or 38–168mm equivalent.

The lens offers a hefty hand feel that bespeaks top-line construction. Large, it resembles a standard-range f/2.8 zoom, and in fact is slightly heavier than Tamron’s 24–70mm f/2.8. With a beautiful matte black finish and crisp barrel markings, the lens is undeniably handsome. Its zoom action is silky, but the manual focus ring is relatively small and stiff-turning. The non-rotating front filter ring and quick, quiet hypersonic focusing motor are nice perks. Oddly, it goes without a moisture-resisting O-ring at the lensmount.

On our optical bench, the lens turned in very good—in some cases, nearly flawless—numbers. Light falloff was gone by f/8 (24mm), f/6.3 (70mm), and f/5.6 (105mm). Not great results, but significantly better than Canon’s comparable 24–105mm f/4L, which at 24mm showed vignetting out to f/13. Its maximum subject magnification of 1:3.89 (105mm) again trounced the Canon’s 1:4.6. Its OS system also significantly outperformed Canon’s: 2 extra stops of hand-holdability, compared to 1.33.

As a standard-range zoom, this lens is suitable for the majority of common subjects. What really caught our eye, though, was its compatibility with a new Sigma feature: mount conversion. Should you ever decide to change camera bodies, Sigma, for a fee, will switch out internal electronics and the lens mount so your 24–105mm f/4 OS will work on your new body, be it Canon, Nikon, Sigma, or Sony. Pretty cool.

SPECIFICATIONS

24–105mm (25.17–104.98mm tested), f/4 (f/3.85–3.93 tested), 19 elements in 14 groups. Focus ring turns 90 degrees. Zoom ring turns 80 degrees. Focal length marked at 24-, 35-, 50-, 70-, 80-, and 105mm.
Diagonal view angle: 84–23 degrees
Weight: 1.98 lbs Filter size: 82mm
Mounts: Canon AF, Nikon AF, Sigma AF, Sony AF
Included: Lenshood, case
Street price: $899
Website: sigmaphoto.com

TEST RESULTS

Distortion: At 24mm, 0.60% (Visible) barrel; at 70mm, 0.30% (Slight) pincushion; at 105mm, 0.28% (Slight) pincushion.
Light falloff: At 24mm, gone by f/8; at 70mm, gone by f/6.3; at 105mm, gone by f/5.6
Close-focusing distance: 16.08 inches
Maximum magnification ratio: At 24mm, 1:11.7; at 70mm, 1:4.91; at 105mm, 1:3.89
IMAGE STABILIZATION: 2 stops

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